Post for interchangeable teeth



Oct. 13, 1931. B. K. TAKENAKA v1,827,119

POST FOR INTERCHANGEABLE TEETH Filed Aprij. 10, 1929 1N VEN TOR A ORNEY li'atent'ed Oct. 13, 193i PATENT orncs BENJAMIN x. TAKZENAKA, on NEW ROCHELLE; NEW YORK ros'r iron INTERQHANGEABLE TEETH" abinidatioir med April 10,

v This invention relates to interchangeable artificial tooth facings' and casting post's whereby said facings may 'be firmly jandi readily secured to cast metal bases or back-'- ings, which in turn are'adapted-to be secured to a d'enture,p0rtion of bridgewor'k or'other dental structure;

An object of'this invention isto providea strong rigidartificial backing of cast gold or other metal or .of mo'ldable-material winch can be hardened, which is designed for heavy duty and which cannotcr'ack or deform under the stress imposed'by biting .or chewa snug and firm fit for the interchangeable 2 tooth facing. v

Other features of this invention Willi-be; readily understood by those familiar with the art these include a simplicity'of' construction and ease of replacing damaged facings, and economy of'manufacture, V

anterioror posterior, teeth and relates to the art of interchangeable tooth bridge construction, but its adaptability for other" dental structures is apparent from the accompanying description. W

The manner of carryingoutthejabove mentioned objects will appear fromthenovelde sign, construction and combination of parts hereinafter described and claimed and shown in the accompanying jdrawingls,in which,

' Figure 1 is an elevational view, partly in section, taken in avertical plane through the approximate center of ,a cast molar'tooth made in accordance With this inventio1i,;showing one form of casting post unit inposition. Figure 2 is a vlitica'l sectionalvi ew .of an incisor tooth, similarlyconstructedaj Figure 3 is a transverse isectionahview on line 3-3 of Figure 1;

Theginvention is adapted for artificial 1929; serial No. 353,959.'

Figure 4 is a perspective View of thecasti ng post nn-itshown in Figu resfl,'2 and 3.

Figure 5 is a perspective view of a m'odifi cat onof g the casting postunit shown in Figures '1,'2,3a nd 4." A

Figurefi is-a trans-verse sectional view similar toFigure 3- with the modified form of casting :post unit in place in the finished easting; This view is taken to illustrate two different half sections as indicated by line 6 6 of Figure 7 igure 7 is an elevational View of their-1'- si-de of a facing before'it' is fixed in the'casting; With the modified casting post-unit fitted in place in a facing.- 1 r 'gure8 isa perspective view of the'i'nner iide'of a grooved facing used w-iththisi-nven- Figure 9 is a sectional view ofapo-rtion' of thehuman jaw, showing the invention in dotted outline in position'inside of'cast i-nciser teeth; ,7

Figured-0 is a" perspective view of a nam ber of teeth-in the lower jaw, showing two 7 cast molars attached as an inlay.

fin the drawings 1 indicates the casting post/,2 a ribconnecting the'pos-t to the plate,

3. The-post, rib and platea'reherein referred to collectively as a casting post unit or as 0' a post unit. The plate 3, as shown in Figure 4, i sp-r ov-1ded with'bevelededges 4. The provision-of these beveled edges produces a positive; interlock into the metal tooth-casting as =1s apparent in Figures 1, 2 and- 3 wherein the metal casting?) is shown to have filled in n front o-f the tapered facing 4 of the casting post unit so to rigidly fix it to the casting. This'construction not only ensnresposr tive anchoring o'f -the casting post unitinto b the casting, but also providesa'smooth, wellformed planar face 6 against which the f'a'cingy'f can seat, without the necessity of filing or grinding to fit. The facing '7 is made of porcelain or similar material i is illustrated in perspective in Figure 8. It

1 contains a longitudinal groove 9'wit h an undercjut tn'bular space 10 thereunderadapted to fit over post 1. These facings'are manlil: fac'tured to fit tightly against the faces *6 I00 groove provided therefor in the of the post units, which are embedded in the castings as follows:

A desired facing is positioned over the post of the casting post unit and said unit is embedded in wax in order that the wax hold the unit in place by filling in in front of the beveled edges 4. The wax is molded into the form of the tooth desired to be constructed, the facing removed and the wax model and casting post unit embedded in a creamy mixture of casting investment which fills in about the post 1 and around the wax model, making an exact form therefor. The investment is allowed to set and when hard and dry is thrust into a fire. During this operation the wax is burned out, the products of combustion escaping through a small hole provided in the investment mold by Withdrawing a very small rod previously inserted in the wax model. The casting post unit is "thus held in proper position by reason of the investment mold holding the pintle in the position in which it had been held by the wax model. A suitable metal is cast into the mold through the hole through which the burning wax escaped, and fills in the inter-- must of necessity possess the identical accustices formerly occupied by the wax model, and as illustrated in Figures 1, 2 and 3. Thus the unit practically dovetails into the backmg.

When locked in the castings as above described the posts 1 are securely held in the front face of the casting, and seating surfaces 6 are provided against which the facings may be accurately and firmly positioned. It is to be noted that the front of the casting post plate is in exact alignment with the front edge of the casting and thus forms a partial backing for the facing. The facing, having been fitted in its place against the wax mold,

rate fit against the finished casting. Thus an exact fit is obtained without having to file or grind down any part of the backing.

In the modification illustrated in Figures 5, 6 and 7 the casting post unit is provided, instead of beveled edges, with beaded or punched-out portions 8 which have the appearance of semi-circular tabs as viewed from the back as in Figure 7. In a manner similar to that in which the metal casting covers the front edges of the bevels 4 in the unit shown in Figure at, so does the casting fill in the spaces above and in front of the tabs 8 and lock this unit in place. This locking is clearly shown in Figure 6.

It has heretofore been attempted to provide fins on casting posts, designed to extend into metal castings for the purpose of anchoring same. These fins have proved highly inef- I ficient and unsatisfactory inasmuch as a posi tive locking-in could not be obtained, and also for the reason that said fins have been found to, interfere with the bite of the user. Even if filed down, the ends of these fins have been subjected to pressure during mastication whereby the casting post has eventually been worked loose from its position in the casting, necessitating a complete reconstruction of the dental structure. Figure 9 shows how this invention completely eliminates this difficulty and makes it impossible for the plate units to become dislodged. This figure illustrates how the casting post unit does not interfere with the bite, even in cases of close bite as indicated in dotted outline at a a. A rigid metal biting or chewing surface is thus provided, together with a removable facing which can be easily replaced by substituting another and cementing it in place. Cast construction is stronger than the usual vulcanite plate, and the interlocked casting post unit is superior to present soldered fastenings or extended fin attachments.

Figure 10 illustrates how a pair of cast teeth, 11 and 12, made in accordance with this invention, can be attached to gold inlays 13 and 14: provided in complementary cavities in adjacent teeth. The construction shown is illustrative merely of a fixed construction but the invention may also be built on a cast metal base or removable bridgework. It should be understood that these cast backings may be secured in place by other means such as crowns fitted on abutment teeth or on plates or other means of attachment known to the art.

The postis preferably made of a high fusing alloy, rich in platinum, with a melting point of 250 degrees Fahrenheit over pure gold, so that it can be invested with the wax model and cast against without danger of partial fusion or distortion.

Obviously this invention is not limited to the precise casting of metal teeth herein illustrated, but may as well be utilized in attaching facing securing means to plates or other dental construction. Vulcanite plates can be molded around the interlocking means to secure effective and permanent attachment thereto. Moreover, it is not indispensable that the various features of this invention be used conjointly, as they may be used to advantage in various combinations and subcombinations.

I claim:

1. An artificial tooth construction comprising a cast backing, a substantially fiat plate anchored in and having a flat surface flush with a surface of said backing, said plate be- 2 ing anchored by projecting portions interlocking with said backing, a web extendin from said plate, a post formed on said we and being substantially narrower than said plate, and a slotted facing longitudinally slidable along said post and against the fiush surfaces of said plate and backing.

2. An artificial tooth construction comprising a cast. backing, a substantially flat plate anchored in and having a fiat surface flush with a surface of'sad backing, said plate being anchored by portions projecting from the edges of said plate and below the surface thereof and'interlocking with said backing,

a web extending from said plate, a post formed on said web and being substantially narrower than said plate, and a slotted facing longitudinally slidable along said post and 

